Hi Steffen, in most cases these motors are collector-less spindle motors, where the current through 3 (or 6, 9, 12) stationary coils is synchronized to give a rotating magnetic field which forces the permanent magnets on the rotor to follow the field. Close to the coils the position of the permanent magnets is monitored by three hall effect sensors to give direct feedback to the controller chip, while there might be one more hall effect sensor to monitor the speed for the central CPU. You'll find the same type of motor driving the spindle in floppy disk and CD drives. The current switching can be done in a single ic or for higher loads with three external transistors (mostly MOSFET).
A low-value resistor might be used to monitor the current through the coils in order to detect a malfunction. The motor might also be a "normal" dc motor, which is coupled to a speed encoder, which either is a small generator or an optical encoder. These types are often driving the capstan spindle in video and audio cassette drives. In those cases the motor speed is regulated by the applied dc voltage to the motor. If you can see the motor, you might be able to conclude which type it is: a) the collector-less type normally has three wires to the three coils and three (plus one common) wires back from the hall sensors. On the circuit board you might find three similar power transistors. b) the dc motor has two wires to the motor and two more wires going to a separate part attached to the motor axis. Uwe. SM> Two whom it may concern SM> I have an old Kyocera laser printer F-3300. It shows error "E2". Due to SM> information from the internet, this means "polygon motor does not SM> syncronize". SM> I hear the polygon motor speeding up. But cannot say, weather it reaches its SM> final speed or not; but from the sound, i guess it goes faster than usual SM> and then stops after a time limit. SM> On the mainboard, i found a bad resistor marked "R99". It still has a value SM> of roughly 5 Ohms (4.7 ???), but i cannot read the value, bacause it's SM> totally burnt and black. SM> Does anyone know, how is the speed of this polygon motor controlled (at SM> least in general, if not in this model). Where is the PLL, and how is the SM> speed signal picked up? Is this a common problem? SM> Thanks a lot! SM> Steffen -- Mit freundlichen Gr�ssen Uwe Zimmermann mailto:[EMAIL PROTECTED] -- Author: Uwe Zimmermann INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
